Takedown can be completed without too much trouble with other players that are equally as good as you. I’d recommend Blast Master with either weapon damage, smg, or assault damage. The skill points of the class mod is not as important as the damage perks.
Skill points: for a well balanced game play with good healing ability from Vampyr here is an example of skill trees that work well.
Assuming the Blast Master class mod has points in Vampyr, you could save some points by not going beyond 3-5 points in it and use those points to grab Click-Click or Experimental Munitions for more damage/less healing. Although Short Fuse gives you damage boost too, but, arguably you’ll get better results by adding increased weapon damage.
For gear I recommend the following: Kybs SMG corrosive, shock and incendiary variants, Ogre assault rifle. Faisor assault rifles (again corrosive, shock and incendiary). Ghast Call Grenades, or maddening tracker, or hex, or anything that has +25% weapon damage on throw. ion Cannon any variant but corrosive preferred. For a shield I recommend a recharger, perks and anointments catered to your preference but do-able without any. Artifact I recommend a last-stand, one that has smg or assault damage boost and grenade damage boost and AOE boost. Or 1 or 2 of those. +40% mags can help extend your fire time maximizing damage.
Keep in mind, Blast Master boosts your splash damage up to 100%. It takes about 1 Minute to get there. When you re-load, you reset the boost. You want splash guns that you can fire for awhile or, swap weapons before your mag runs dry and let your ammo regen through Means of Destruction Redistribution. A gun like the Ogre has such a large mag that you might not ever need to reload while firing for several minutes at a time.
Theoretically you will be regenerating enough Grenades to keep your health up and assist in constant damage by throwing one every 30 seconds to 1 minute. I’ve found if you spam grenades too quickly, they have a harder time to regen. You’ll want to enter Wotan fight with a full supply. Thankfully there is an ammo machine right before it.
Use iron bear for oh-sh*t situations. Buys you time to run away or take a breather.
Keep your distance from enemies and be mindful of the mini map and your enemies location.
Other than that, shouldn’t be too difficult. Good luck!